The bow on an Atlantic 85 contains ballast tanks which are filled with water to provide the boat with more stability and may be filled and emptied while at sea by the use of the handle near the helmsman which lowers a scoop to fill the tanks while the boat is underway

So what happens if it turns over is there a trip switch on the engines

Yes there is a "tilt switch" which shuts the engines down in that scenario.

Indeed they were a bit of an issue with the early Atlantics as these switches were sometimes too sensitive and used to inadvertently shut the engines down when the boats were going up wind and were reaching nearly vertical angles as a result - just what you don't need to happen in that situation